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In medicine, the Leksell Gamma Knife is a neurosurgical device used to treat brain tumors. It was invented by Lars Leksell, a Swedish neurosurgeon, in 1967 at the Karolinska Institute in Sweden.

The Leksell Gamma Knife unit contains 201 cobalt-60 sources of approximately 30 curies (1.1 TBq) each, placed in a circular array in a heavily shielded assembly. The unit directs gamma radiation to a target point through a procedure in which the patient wears a specialized helmet on their head to direct the radiation. Such target points selected in the brain can be placed at the center of the radiation focus, allowing a tumoricidal radiation dosage to be delivered in one treatment session. The Gamma Knife has proved effective for thousands of patients with benign or malignant brain tumors, vascular malformations such as an arteriovenous malformation (AVM), pain or other functional problems.

The procedure is less invasive than alternative surgeries like micro-decompression for neurological disorders. In the case of treatment for Trigeminal neuralgia the procedure may be used repeatedly on patients.

Ultimately, consideration for Gamma Knife radiosurgery treatment is contingent upon the patient's diagnosis, medical history and the case's overall severity upon consultation. In some instances, neurosurgeons will consider treatment for patients with metastatic disease, the elderly and whose life span will not exceed fifteen years, as well as those with inoperable lesions.

The risks of Gamma Knife radiosurgery treatment include but are not limited to radiation necrosis, secondary malignancy caused by the radiation (ie: formation of new tumor), hemorrhage, infection from the placement of the stereotactic headframe, paralysis and death.

Contents 1 How It Works 2 Studies 3 Accuracy 4 Statistics 5 Present Day Business 6 See also 7 References 8 External links

Leksell Gamma Knife emits finely focused beams of gamma radiation with minimal effect on surrounding normal tissue and without the usual risks of surgery or an incision. Gamma Knife radiosurgery maximizes patient comfort and can be used to treat lesions that before were either inaccessible or were treated unsuccessfully by conventional surgery, chemotherapy and/or radiation therapy.

Leksell Gamma Knife has been reviewed in over 2,000 publications with long-term follow-up studies on patients all demonstrating high clinical success rates.^{[citation needed]}

Leksell Gamma Knife guarantees accuray to better than 0.5mm and has found the actual achievable accuracy to be 0.15mm. Because of the Leksell Gamma Knife system's accuracy and proven track record, physicians are confident in administering a single radiation dose that is solely confined on the tumor.^{[citation needed]}

• Nearly half a million patients treated over 30+ years^{[citation needed]}
• Covered by all insurance providers^{[citation needed]}

Elekta, manufacturer of Leksell Gamma Knife, is currently the second largest supplier of radiotherapy equipment in the world, and the market leader in Europe.^{[citation needed]} Leksell Gamma Knife remains the gold standard for stereotactic neurosurgery against which all other systems are compared.^{[citation needed]} The new Elekta Leksell Gamma Knife Perfexion system increases the available treatment volume, allowing many more sites of treatment.

• Brain Tumor
• Cyberknife
• External beam radiotherapy
• Horsley-Clarke apparatus
• Linear accelerator
• Minimally invasive procedure
• Neurosurgery
• Novalis radiosurgery
• Radiation therapy
• Robotic surgery
• Stereotactic surgery

• Rowe et al. Risk of Malignancy after Gamma Knife Radiosurgery, Neurosurgery. 60(1):60-66, January 2007.

• Gamma Knife Site
• How Gamma Knife Works (Video)
• Elekta Official Web Site